It's often been noted, rightly, that Donald Trump's "America First" approach to foreign policy is a repudiation of the internationalist approach -- that it is in the United States' interest to construct and lead a cooperative international system that promotes trade and diffuses conflict -- that all American presidents have taken since the Second World War. It's also been noted that Trump's approach is a revival of thinking that was widespread, even predominant, through most of American history until the Second World War. In this thinking, "foreign entanglements" could only drag America into ruinous wars. America should entrust its security to the oceans and its navy. The world could do as it wished. America would do the same. But there's one aspect of this thinking that is jarringly different than Trump's: Aside from a strong navy to protect America's coasts and shipping, isolationists didn't want a large military. Indeed, traditionally, they saw standing armies as the hallmarks of European tyrannies. They despised them. Many even found professional soldiers to be somewhat dubious. What they preferred -- and what the United States did until the Second World War -- was to have a relatively tiny force. And a relatively tiny armaments industry. In the event of a land war, America's abundant population and financial resources would be tapped and a big new army of recruits armed with weapons bought both domestically and from foreigners would be marshalled. Once the war was over, the army would mostly be disbanded. This is how the United States fought the Civil War, the Spanish-American War, and, particularly, the First World War. This all changed after the Second World War. To create and lead an international system, and fight the Cold War, the United States needed an enormous force and the defence industries to keep it equipped with the latest weaponry. A big part of that force was professional, although it was supported by a draft. When the draft was abolished after the Vietnam War, the military became an entirely professional force of enormous size and power. A cultural shift occurred at the same time: Professional soldiers became highly respected; the military is now one of the most trusted institutions in the United States. Trump doesn't propose to change any of that. In fact, he claims the military is under-resourced and he says he will greatly expand both its personnel and resources. The contrast with traditional isolationism is stark. The absence of commentary about the contrast is, I suspect, because the traditional American suspicion of large standing armies is long forgotten. But this is more than an historical quirk. After all, it invites an obvious question: If you want America to end its foreign entanglements, to let the world do as it wishes while America does the same, why spend half a trillion dollars a year to support an immense force based all around the globe? PS, June 15: Based on Trump's behaviour and statements, I have my answer. He's not an isolationist. Nor does he support the international system which the United States founded and led. His worldview seems to be something else entirely -- if indeed it is sufficiently coherent to be described as a worldview and not merely a sequence of contradictory impulses.